If you are on macOS Mojave 10.14.3 (or earlier in the 10.14 chain):
: If the App Store link doesn't work, you can fetch the full installer using this command on newer macOS versions: Macos Mojave 10.14 4 Iso Download
Developers need specific OS versions to test software compatibility. ⚠️ Disclaimer: Direct Download Notice If you are on macOS Mojave 10
Create a bootable USB installer for recovering older Mac hardware. Macos Mojave 10.14 4 Iso Download
sudo dd if=/dev/rdisk2 of=~/Desktop/macOS_Mojave.iso bs=1m